The Scoters of Québec

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Onglets

Description

Distinguishing features

Scoters are sturdy sea ducks. The three species that breed in Québec are well adapted for diving in cold waters. They share a stocky build, narrow wings, and a prominent bill. However, each species has its own distinctive features, especially in the shape of the bill and head.

The scoter species found in Québec share a similar body shape, reflecting similar habits. Subtle differences can help you tell them apart:

White-winged Scoter (Melanitta deglandi): the largest of the three species, it has a dark chocolate-brown plumage with a white patch on the wings. Males have a white mark under the eyes.

Surf Scoter (Melanitta perspicillata): the only species in which the male has a white patch on the forehead. Males have a thick, orange and white bill. Females are more muted in colour, with a less pronounced forehead slope than males.

Black Scoter (Melanitta americana): Males have a bright yellow protuberance on their bill that stands out against their dark plumage. Unlike the other two species, females have pale cheeks that contrast with their dark cap.

Reproduction

The three scoter species found in Québec follow a similar breeding cycle: pairs form on the wintering grounds, and in April the birds migrate to their respective breeding habitats:

White-winged Scoter: breeds in the taiga and inland boreal forest, near ponds;

Surf Scoter: prefers the Arctic tundra, often far from trees.

Black Scoter: tends to breed on deep, isolated lakes in the boreal forest.

After mating, the males quickly leave the female and head to coastal areas, where they moult in large or small rafts, depending on the species. They leave incubation entirely to the females, which generally lay 5 to 10 eggs.

The females incubate the eggs on their own, leaving the nest only briefly to feed. The incubation period lasts about 27 days.

As soon as they hatch, the precocial ducklings make their way to the water, where they feed independently. They sometimes gather into nursery groups called “crèches” under the watch of several females. The young remain dependent on maternal protection until fledging, which occurs at about 7 to 8 weeks of age.

Autumn migration follows a typical sequence: males leave as soon as their moult is complete, in July or August, while females and their young depart the breeding grounds between late August and September, depending on latitude and the length of the northern season.

Diet

All three are diving species well adapted to capturing aquatic invertebrates. However, their choice of prey reflects their ecological niche:

White-winged Scoter: feeds on benthic molluscs, especially mussels.

Surf Scoter: feeds on crustaceans and other marine invertebrates, such as amphipods and juvenile crabs, as well as fish eggs.

Black Scoter: stands out for its more varied diet, which includes small fish and deep-water invertebrates.

This dietary partitioning reduces competition among the three species when they share marine habitats.

Predators

Eggs and ducklings face the same terrestrial predators, including crows, foxes, mustelids (small carnivorous mammals), and northern birds of prey. Adults are rarely preyed upon, but they may be attacked by large raptors or injured by human activity. The level of risk depends more on habitat than on species.

Habitat

These sea ducks use similar marine habitats, but their breeding areas vary by species.

Outside the breeding season, from September to April, the three species may share the same range (that is, they are sympatric). They then gather in large rafts in the St. Lawrence Estuary and Gulf, and sometimes even along the Atlantic coast.

During the breeding season, however, these scoters generally occupy distinct ecological areas (in other words, they are allopatric). This minimizes competition for breeding sites and improves the young’s chances of survival.

Ecology, behaviour

All three species are excellent divers and can reach depths of 20 to 40 metres. Outside the breeding season, they are gregarious, forming vast and impressive rafts.

White-winged Scoter: the most gregarious and the most numerous of the three, it forms the largest gatherings.

Surf Scoter: the most vocal, it is strongly associated with open marine habitats.

Black Scoter: nearly 80% of the world’s population breeds in Canada.

These birds play an important ecological role by helping to control marine invertebrate populations. They also serve as indicators of the health of northern coastal environments.

French name

Macreuse à ailes blanches, macreuse à front blanc, macreuse à bec jaune

Scientific name

Melanitta deglandi, Melanitta perspicillata, Melanitta americana

Phylum

Chordata

Class

Birds

Order

Anseriformes

Family

Anatidae (geese and ducks)

Size

White-winged Scoter: 43 to 49 cm Surf Scoter: 47 to 55 cm Black Scoter: 50 to 58 cm

Weight

White-winged Scoter: 800 to 1,350 g Surf Scoter: 800 to 1,650 g Black Scoter: 950 to 2,300 g

Life span

In the wild: generally 10 to 15 years (with records of around 20 years)

Status

Least Concern (for all three species)

At the Biodôme

All three scoter species are represented in the large basin of the Gulf of St. Lawrence ecosystem. They share the space with Common Eiders and other sea ducks. All individuals come from a wildlife rescue centre and have abnormalities that prevent their release into the wild.

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